Insulated cable with wire for slitting a protective sheath

ABSTRACT

A cable having an outer protective covering or sheath enclosing one or more insulated conductors and a cutting wire or rip cord intended for slitting the covering, the cutting wire being located under a longitudinal notch on the inner side of the covering with the position of the cutting wire being marked on the outer surface of the covering, the marking having the form of a longitudinal notch or two parallel ridges.

United States Patent [1 Krook et al. v

INSULATED CABLE WITH WIRE FOR SLITTING A PROTECTIVE SHEATH Inventors:Otto Erik Krook, Hagersten; Sven Sigurd Noroblad, Spanga, both of SwedenTeletona ktiebolaget iLM Ericsson, Stockholm, Sweden Filed: May 18, 1972Appl. No.: 254,422

Assignee:

US. Cl 174/70 R, 174/10, 174/112 Int. Cl. H01]! 7/00, HOZg 1/12 Field ofSearch 174/10, 112, 70 R References Cited UNITED STATES PATENTS 8/1934Soutter, Jr. 174/10 July 24, 1973 2,147,337 2/1939 Charmoy 174/112Primary Examiner-Laramie E. Askin [57] ABSTRACT 5 Claims, 4 DrawingFigures INSULATED CABLE WITI-I WIRE FOR SLITTING A PROTECTIVE SHEATIIThe present invention refers to cables and especially to that kind ofcables which comprise a protective covering or sheath, preferably ofplastic material which covering encloses one or more conductorspreferably plastic-insulated, and a wire, a thread or the like intendedfor the cutting up of the covering. The covering may preferably have alongitudinal part that is thinner than the rest of the covering. Whenpulling the wire in a direction out from the covering, the wire willslit the covering at its thinner part.

It is previously known to cut up the covering of plastic-insulatedcables with the aid of an edge-tool but such edge-tools often causeinconveniences due to the fact that the underlying conductors easily canbedamaged unintentionally. This could be eliminated if the covering wasprovided with indications which indicated where the cutting was to bedone, for example immediately above the cutting wire and along the same.Upon the slitting of cables where a thread or a cutting wire is used,the covering will be opened to such an extent that the end of thecutting wire'can be grasped with a pair of fingers or the like and bypulling the cutting wire, mainly perpendicularly to the cable, the wireis caused to cut through the covering. It has however been found thatalso the using of a cutting wire may involve certain inconveniencessince it often is very difficult to localize the position of the wireunder the covering. The short slitting of the covering that must beexecuted with a tool when trying to find the end of the cutting wireserves, it is true, as an indication for the latter cutting up with theaid'of the cutting wire but the first cutting corresponds very seldom tothe real position of the cutting wire. v

' The present invention has for a purpose to eliminate the disadvantagesindicated above.

What principally may be considered to be the characteristics of thecable according to the present invention is indicated in thecharacterizing part of the following claim 1.

In the accompanying drawing two embodiments of the invention will beillustrated more closely.

FIG. 1 showsthe cross-section of a cable by means of a firstembodiment.

FIG. 2 shows the cross-section of a cable by means of a secondembodiment. I FIG. 3 shows the cable according to FIG. 1 when a cuttingtool is allowed to affect the covering and furthermore FIG. 4 shows onan enlarged scale thecross-section of a suitably shaped cutting wire. I

In FIG. 1 the cross-section of a cable is shown. This cable shows anouter protective covering or sheath 1, preferably of plastic material,one or more conductors enclosed by. the covering, with the commonreference numeral 2 and preferably plastic-insulated, and a cutting wire3 located immediately underneath the covering. The covering 1 has a part4 which is thinner than the rest of the covering. This thinner part 4 isformed by arranging a notch 4a on the inner side of the covermg.

The outer surface of the covering 1 is further provided with two ridges5,5a located on both sides of the thinner part 4 and running parallelly,serving as marking for the cutting wire3.

In FIG. 2 a second embodiment of a cable is shown in cross-section. Themarking has here the form of a longitudinal notch 4b in the outersurface of the covering. It is evident that this longitudinal notchaffords the thinning of the covering, required'for the cutting up of thesame, but in order to facilitate the placing of the cutting wire 3 under4b the covering is suitably provided with a notch 4a on the inside.

The cutting wire 3 can consist of'different materials and according tothe invention it is proposed that the wire consists of nylon, glassfibre or the like.

According to FIG. 4 the wire 3 can comprise a central part 3a enclosedby a coating 3bwhere the central ,part is composed of glass fibre, nylonor the like while the coating 3b with advantage can consist of plasticmaterial. By placing'such awire 3 according= to FIG. 4 inthenotch4athewire 3 can serve to protect the enclosed conductors 2'frombeingcut through which is illustrated in connectionwith FIG. 3.

It is suitable, provided that the cutting wire isdesigned. according toFIG. 4 that the wire with its coating is so adapted that it is possibleto insert or center it in the notch 4a.

InFIG. 3 is then shown howa cable according to FIG. 1 with awireaccording to FIG. 4 is cut by means of a tool 6. The cutting tool 6comprises a cutting edge 6a which can be adjusted to the desired depthof cut in knownmanner. It is here the purpose of the ridges, 5,521 tocontrol thetool 6 while the wire 3, of the kind described in FIG. 4,serves to protect underlying parts'2 in the cable. from beingslit orcut.In sucha, case an-arbitrarily short cable can'be unsheathed since thewire 3 is not at all exposed to pulling.

Upon the manufacture of the cable the covering, as it is shown earlier,can be made-thinner. The wire 3 is suitably placed in the notch 4a attheextruder head. If the cutting wire is brought to the conductors '2before the covering is extruded it is essential that the cutting wirereally comes into co-operation with the notch. The extruder head formingthe covering may also be designed in such a way as to form on the onehand a notch 40 on the inner surface of the covering, and on the otherhand to form ridges 5,5a on the outer surface of the covering, locatedbeside each other and on either side of the notch. Furthermore, theextruder head can be designed to form a notch 4b on the outer side ofthe covering and to form a further notch 4a on the inner side of thecovering. With this embodiment it can'be suitable to let the notches beof different sizes and as shown in FIG.2. 7

Upon the extrusion of the covering the wire is permitted to pass intothe extruder head so that it will place itself automaticallyin the notch4a. Since, according to the invention, the outer part of the coveringshall either be provided with ridges 5,511 or with a notch 4b inconnection with the cutting wire it is easy to localizethe position ofthe wire and to cut by means of a knife or the like the thinned part somuch that the wire easily can be seized. Because the covering is thinnedin connection with the wire the tractive force required will be reduced,in consequence of which slitting of also short cables can be executedwith the aid of the cutting wire without the wire slipping out of thecable. in case ridges 5,5a are selected for the outer surface of thecable these will also form a protection against unintentional mechanicalinfluence on the thinned part. i

The invention is of course not limited to the embodiments indicatedabove as examples but can have modifications within the scope of thefollowing claims.

We claim:

1. An electrical cable comprising at least one insulated conductor, acutting wire extending longitudinally along said insulated conductor,and a protective sheath surrounding said insulated conductor and cuttingwire, the inner surface of said sheath being provided with a firstlongitudinally extending groove for accommodating said cutting wire toconstrain the location thereof, and the outer surface of said sheathbeing provided with longitudinally extending means for mechanicallyguiding the movement of a cutting tool to a longitudinal furthersheathed with a protective layer.

1. An electrical cable comprising at least one insulated conductor, acutting wiRe extending longitudinally along said insulated conductor,and a protective sheath surrounding said insulated conductor and cuttingwire, the inner surface of said sheath being provided with a firstlongitudinally extending groove for accommodating said cutting wire toconstrain the location thereof, and the outer surface of said sheathbeing provided with longitudinally extending means for mechanicallyguiding the movement of a cutting tool to a longitudinal path oppositesaid cutting wire.
 2. The cable of claim 1 wherein said longitudinallyextending means comprises a second longitudinally extending grooveparallel to said first longitudinally extending groove.
 3. The cable ofclaim 1 wherein said longitudinally extending means comprises twolongitudinally extending ridges parallel to and straddling said firstlongitudinally extending groove.
 4. The cable of claim 1 wherein saidcutting wire is of a fibrous insulating material.
 5. The cable of claim1 wherein said cutting wire is further sheathed with a protective layer.